使用從臨時表派生的值循環遍歷 sql server 表

Question

我需要使用從臨時表派生的值並將其用作 where 條件。 請看我的代碼：

declare @laneNum int
declare @startDate date = '2019-02-07'
declare @class int = 1
declare @id int 

if OBJECT_ID('tempdb..#tempLaneNumber') IS NOT NULL
drop table [#tempLaneNumber]

create table #tempLaneNumber
(
    LANE_NUMBER INT NULL
)


INSERT INTO #tempLaneNumber (LANE_NUMBER)
SELECT DISTINCT EXIT_LANE
FROM [dbo].[TOLL] 
ORDER BY EXIT_LANE ASC

select * from #tempLaneNumber

set @laneNum = (select * from #tempLaneNumber)

begin
    select COUNT(*)
    from [dbo].[TOLL]
    where convert(date, TRXN_DTIME) = @startDate and EXIT_LANE = @laneNum
end

如果我跑起來select * from #tempLaneNumber我得到這個結果：

但是，如果我將此值用作 where 語句的標准，則在 begin 語句中，我不會得到預期的結果。

Answer 1

您需要更改您的查詢，如下所示。

select l.LANE_NUMBER, COUNT(*)
    from [dbo].[TOLL] t
    inner join  #tempLaneNumber l on t.EXIT_LANE = l.LANE_NUMBER
    where convert(date, TRXN_DTIME) = @startDate 
    GROUP BY l.LANE_NUMBER

您的查詢中有多個問題，我已對這些問題進行了評論並在需要時進行了修改。

--declare @laneNum int [NOT REQUIRED]
declare @startDate date = '2019-02-07'
declare @class int = 1
declare @id int 

if OBJECT_ID('tempdb..#tempLaneNumber') IS NOT NULL
drop table [#tempLaneNumber]

create table #tempLaneNumber
(
    LANE_NUMBER INT NULL
)


INSERT INTO #tempLaneNumber (LANE_NUMBER)
SELECT DISTINCT EXIT_LANE
FROM [dbo].[TOLL] 
--ORDER BY EXIT_LANE ASC [NOT REQUIRED FOR INSERT]

select * from #tempLaneNumber

--set @laneNum = (select * from #tempLaneNumber) [YOU CAN'T ASSING A TABLE OUTPUT TO A INT VARIABLE]

--begin [NOT REQUIRED]
/*
    select COUNT(*)
    from [dbo].[TOLL]
    where convert(date, TRXN_DTIME) = @startDate and EXIT_LANE = @laneNum
*/
--CHANGED
select l.LANE_NUMBER, COUNT(*)
    from [dbo].[TOLL] t
    inner join  #tempLaneNumber l on t.EXIT_LANE = l.LANE_NUMBER
    where convert(date, TRXN_DTIME) = @startDate 
    GROUP BY l.LANE_NUMBER
--end [NOT REQUIRED]